The real problem is in the CPLD, the code do a lot of things wrong, and we can't update the existing one in the field (nor I would recommend to be honest).

[hr]

After looking at the signal on an oric that "fail" the signal that arrive on the cumulus is clean, there is no weird issue there, but the signal is slightly temporarily shifted from another oric that works, the CPLD code handling Phi2 is doing something, if not wrong, terribly incorrect and can't cope well if Phi2 is not in the window that this code expect.

If you remember on the Microdisc, there is a potentiometer to set the Phi2 shift internally. That is because not all oric have the exact same timing on Phi2, there is a general setting that work for most, but some are problematic and we need to trim that potentiometer. The current cumulus CPLD does not permit that.

Edit2: your change is basically adding some delay to the Phi2 signal,and is somewhat similar to what the Microdisc is doing. Don't set a fixed value to the resistor, but use a potentiometer to be able to adjust the timing or your change will fail on some oric that were working before if your change put Phi2 out of the window that the cumulus is expecting.